1. Field of the Invention
The present invention relates to fluid connectors and, specifically, to the sealing interconnection of such connectors with tubing end forms and, more specifically, to the use of spin welding to effect such interconnection.
2. Description of the Art
Quick connect couplings have been widely used in the U.S. Automobile industry for many years. Although applicable in numerous applications, quick connectors are typically employed in fuel systems and vapor recovery systems. The simplest and most cost effective design is the plastic housing female type quick connector releasably mated to a metal or plastic male tube endform. The opposite end of the female housing most typically defines a stem having a number of axially spaced barbs formed on the outer circumferential surface thereof and a nylon or plastic tubing endform pressed thereover.
In fluid handling systems, it is imperative that the connectors used have their male and female portions properly coupled together. A faulty connector enables an associated system to leak fluid or vapor. This can be particularly disadvantageous when the system is under pressure and the leaking connector expels the pressurized fluid. Furthermore, recent federal legislation has mandated significantly reduced hydrocarbon emissions from automotive fuel and vapor recovery systems. Conventional quick connectors, although effective to mechanically maintain tubing endforms in assembly with their associated connector body, have not adequately addressed the federal requirements. Also, the materials employed, typically nylon 12, do not provide sufficient resistance to the permeation of hydrocarbons therethrough.
The permeation problem has been addressed in part through the development of co-extruded multi-layer plastic tube containing two or more discreet layers of different types of formulations of plastic, one of which is specifically designed to provide an effective permeation layer, blocking the escape of hydrocarbons from the system. In general, the most successful multi-layer tubing employs an outer layer composed of a material resistant to the exterior environment. An innermost layer is composed of a material which is chosen for its ability to block defusion of materials, such as hydrocarbons, alcohols and other materials present in fuel blends, to the outer layer and may have a degree of electrical conductivity sufficient to dissipate static charges generated by the flow of fluid therein. To date, it has been extremely difficult to obtain satisfactory lamination characteristics between dissimilar polymer layers. Thus, the use of one or more intermediate layers for bonding the inner and outer layers has been proposed.
The use of multi-layer tubing in fuel related applications has been problematic inasmuch as the tubing endform necessarily exposes the lamina ends of the inner and outer layers as well as any intermediate layers to either the system fuels and vapors or the equally harsh exterior environment. Such exposure tends to degrade the bonding between the various layers, causing delamination or separation of the layers, resulting in loss of system integrity, fuel contamination and even blockage of fluid flow.
A related problem stems from dual aspects of commercially available quick connect devices, to wit: high volume and low sale price frequently necessitating the use of inexpensive, somewhat pliable materials, and complex contours of extremely small inter-fitting components. These aspects collectively increase the likelihood of misassembly. High volume production techniques, including automated assembly tends to aggravate the problem wherein misassembly or impermissible dimensional variations of the components is difficult to detect. Excessive dimensional tolerance stack-up can result in low pull-apart characteristics between the barbed stem and the plastic tube and produce leakage. Misassembly, such as failure to include an O-ring on the barbed endform can result in leakage. In the case of multi-layer tube, dimensional and/or adhesive problems can result in mechanical delamination upon insertion of the tube over the barbed stem. Finally, mono-wall plastic tube or multi-layer structures with low hoop strength can relax over time or at elevated temperatures, resulting in leaking or weeping of fluid.
One prior art approach to address at least certain of these problems is shown in FIG. 1 wherein a quick connector assembly includes a connector which interconnects a steel tubing member endform with a mono-wall plastic tube endform. An upset bead displaced axially from the leading end of the steel tube releasably engages a retainer interconnected with the connector and is fluidically sealed thereto by a series of O-rings in the usual manner.
The opposite end of the connector is formed as an elongated stem or nipple having a plurality of axially spaced, radially outwardly projecting barbs. The plastic endform is slip fit over the outer surface of the nipple and engages the sharp edges of the barbs to mechanically engage the two elements, while an optional O-ring disposed within a radially outwardly opening recess provides a seal between the internal diameter of the plastic endform and the connector.
In order to address certain problems with this prior art design, another quick connector developed by the assignee of the present application is in FIG. 2, also serves to interconnect a steel tubing member endform and a multi-layer plastic tube endform to effect a fluid seal therebetween ideally suited for use in automotive applications, particularly in fuel and vapor applications.
This prior art connector is formed of a hard shell plastic connector body having a stepped bore which receives one end of the male endform at one end. A retainer is releasably mountable in the connector body in engagement with the raised annular flange on the male endform to releasably interconnect the male endform and the connector body.
The rigid plastic tube has an end seated within a specially formed, annular groove in the end of the connector body and spun welded thereto to form an environmentally favorable seal between the two elements as well as to physically join the two elements together.
While the second prior art connector overcomes many disadvantages associated with the earlier prior art connector shown in FIG. 1, the connector assembly shown in FIG. 2 includes a complex connector housing with an internal stepped bore sized in various diameters to receive the sealing elements as well as the male endform and a separate retainer. In addition, the connector body uses the annular end groove specifically formed for the spin welded joint between the connector body and the rigid plastic tubing. Further, the spin welded tubing to quick connector joint is axially in front of the O-ring seal elements which can lead to a fuel/vapor leak if the weld is improperly formed or foils.
Thus, it would still be desirable to provide a simple and inexpensive, yet mechanically and environmentally robust connection between a tube endform and a connector body as well as a quick connector which overcomes the shortcomings of prior art connectors. It would also be desirable to provide a quick connector for use in vapor/fuel applications which uses a minimal number of components; yet is still able to provide the desired environmentally safe fluid seal between the metal male endform and the plastic tube.
The present invention is a quick connector apparatus ideally suited for fuel and vapor applications in automobiles.
One aspect of the present invention is a unique method of forming a quick connector. The method includes the steps of:
inserting a seal member into an open end portion of the first tube member endform;
providing a retainer element with a through bore extending between first and second opposed ends and at least one latch member extending from the first end;
disposing the second end of the retainer element in the end portion of the first tube member endform;
welding the end portion of the first tube member endform to the retainer element; and
inserting a second tube member endform through the bore in the retainer element and into the end portion of the first tube member endform with the latch member on the retainer element engaging a radially enlarged flange on the second tube member endform to couple the second tube member endform to the retainer element.
In another aspect of the present invention, a quick connector apparatus includes:
a first tube member having an end portion terminating at a first end;
a seal member mounted in the end portion of the first tube member;
a retainer element having a through bore extending between first and second opposed ends and at least one latch member extending from the first end with the second end of the retainer element inserted into a bore in end portion of the first tube member and spin welded to the first tube member; and
a second tube member releasably coupled to the retainer element by the latch member.
In one aspect, the end portion of the first tube endform is expanded to an enlarged diameter from a nominal tube diameter. The seal element(s) are inserted into the enlarged diameter end portion.
The quick connector apparatus of the present invention overcomes several deficiencies found in previously devised quick connectors, including quick connectors utilizing spin welding to join various components of the connectors together, and quick connectors designed for specific use in fuel and vapor applications wherein it is necessary to limit fuel permeability through the conduits or tubes. The present quick connector utilizes a minimal number of components and eliminates the need for a complex, high cost housing employed in previous quick connector assemblies which is joined to one of the conduits and which receives the retainer element. The cylindrical sleeve of the retainer element and the inner surface of the open end portion of the conduit are spin welded together to form a gas impermeable seal therebetween. The welded conduit to quick connector housing joint is axially behind the O-ring seal(s) to reduce the possibility of a vapor fuel leak.